Structure of the Human Ear

The Structure of the Human Ear

The Human Ear provides several functions in addition to providing us with the ability to hear including detecting the heads position and motion and providing a sense of balance. Within the ear there are distinct areas that are involved in hearing and balance.

The Outer Ear

The ear is divided up into three different parts. The outer ear is slightly funnel shaped to help guide sound waves into the ear. The ear flap, or lobe as it is sometimes called, is termed the pinna. The pinna is made up of fat, cartilage and connective tissue that are covered in skin. Wax that is secreted just inside the outer ear is responsible for trapping dirt and germs to keep them from entering the ear. Contrary to popular belief ear wax does not need to be removed manually; it will flake off on its own as the jaw moves during talking and chewing. Also part of the outer ear is an S-shaped outer ear canal called the external acoustic meatus. The ear canal helps to guide sound waves into the middle ear.

The Middle Ear

The parts of the middle ear serve to amplify the sound waves that come in. Those sound waves are transferred from the air into the fluid of the inner ear. The main elements in middle ear include the eardrum (known as the tympanic membrane) and the three smallest bones in the human body. The bones are the malleus (hammer), incus (anvil), and the stapes (stirrup). These bones, auditory ossicles, span the middle ear cavity, or the tympanic chamber. The tympanic chamber is connected to the throat be the Eustachian tube and through that to the air outside the human body. Through this connection the atmospheric pressure can be transferred into the cavity and can help to equalize the pressure on either side of the eardrum to avoid damaging it.

The Inner Ear

The inner ear is filled with fluid and is responsible for changing sound waves into nerve signals inside the cochlea. The cochlea contains the organ of hearing and it barely bigger than the tip of the little finger. The vestibule contains to organs the utricle and saccule which are the organs of balance. The Vestibular nerve carries signals from the balance organs into the brain, while the vestibulocochlear nerve sends nerve signals from the vestibule and cochlea to the brain. Other structures inside the inner ear include the tympanic canal, the vestibular canal, and the cochlear duct.